Ethyl Acetate → 5-(5-(3,5-dichlorophenyl)-5-(trifluoromethyl)-4,5-dihydroisoxazol-3-yl)-3,3-diethyl-benzo[c][1,2]oxaborol-1(3H)-ol

Participants

Reaction Conditions

Reaction Steps

To a solution of 3,3-diethyl-1-hydroxy-1,3-dihydrobenzo[c][1,2]oxaborole-5-carbaldehyde oxime (251 mg, 1.07 mmol) in DMF (15 ml) at rt was added NCS (151 mg, 1.13 mmol). The reaction mixture was warmed to 45° C., stirred for 1.5 h and cooled to −10° C. To this mixture was successively added 1,3-dichloro-5-(3,3,3-trifluoroprop-1-en-2-yl)benzene (516 mg, 2.15 mmol) and TEA (326.3 mg, 3.23 mmol) below −10° C. The mixture was stirred at this temperature for 2 h, poured into ice-water and extracted with EA (40 ml×2). The combined organic layers were washed with aqueous NaHCO3 and brine, dried over Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by column chromatography over silica gel eluted with PE:EA (10:1 to 5:1) to give the desired title compound 5-(5-(3,5-dichlorophenyl)-5-(trifluoromethyl)-4,5-dihydroisoxazol-3-yl)-3,3-diethylbenzo[c][1,2]oxaborol-1(3H)-ol (180 mg, yield 35.5%) as white solid. 1H NMR (300 MHz, DMSO-d6): δ 9.22 (s, 1H), 7.85-7.45 (m, 6H), 4.48-4.22 (m, 2H), 2.00-1.70 (m, 4H), 0.68-0.42 (m, 6H) ppm. MS: m/z=472 [M+1]+.

Provenance & Evidence